Connector switch in a viewfinder socket on a photographic camera for an electronic flash gun



Nov. .28, 1967 J. HAHN ETAL 3,355,559

CONNECTOR SWITCH IN A V IEW FINDER SOCKET ON A PHOTOGRAPHIC CAMERA FOR [1N ELECTRONIC FLASH GUN Filed 901:. 29, '1964 United States Patent 3,355,559 CONNECTOR SWITCH IN A VIEWFINDER SOCK- ET ON A PHOTOGRAPHIC CAMERA FOR AN ELECTRONIC FLASH GUN Johann Hahn, Stuttgart, Paul Greger, Braunschweig, and Herbert Weidner, Volkmarode, near Braunschweig, Germany, assignors to Zeiss Ikon Aktiengesellschaft, Stuttgart, Germany Filed Oct. 29, 1964, Ser. No. 407,417 Claims priority, application Germany, Nov. 2, 1963, Z 10,447 1 Claim. (Cl. 200-52) The invention relates to a photographic camera provided with a contact nipple for a cable connected flash gun whose contacts are detachably arranged with contacts provided in a viewfinder socket.

If for example an electron flash gun is connected to the contact nipple of the camera, the contact in the viewfinder socket may be charged with a current of one hundred volts so that if a person accidently touches this contact with his finger of the hand operating the camera undesirable consequences may result because the contact in the viewfinder socket can be short-circuited over ground by the finger touching it. Also when an auxiliary device, for instance a close-up focusing attachment, is attached to the viewfinder socket, the contact in this socket may be connected with the camera casing, thereby effecting an undesired release of a flash gun connected to the contact nipple.

In order to avoid such mishaps, it has been proposed heretofore to provide a switch in the electric connecting line between the viewfinder contact and the contact nipple on the camera casing. Such a switch would, however, have to be additionally operated and its arrangement within the camera is structurally awkward.

It is the object of the invention to avoid these disadvantages in that a switch is built into the viewfinder socket and is operated when the flash gun attachment plug is inserted into the viewfinder socket. If now e.g. an electron flash gun is connected to the contact nipple, the contacts in the viewfinder socket are no longer under voltage so that the mentioned possibilities for a short circuit no longer exist. With the insertion of the attachment plug of the flash gun into the viewfinder socket the switch in this socket is automatically closed.

Preferably, one of the contact strips forming the switchc-onveniently the one connected with the voltage carrying pole of the contact nippleis mounted below the base plate of the viewfinder socket or mounted somewhat recessed in it, respectively, while the other contact strip is arranged on top of the base plate or at least emerges from the bottom plate at the contact point with the yieldable contact of the flash gun. When the flash gun is slidably inserted in the viewfinder socket, both contact strips are caused to come into engagement with each other in the region of an opening provided in the base late. p In accordance with the invention it is possible to employ the yieldable contact on the attachment plug of the flash gun for closing the switch when the attachment plug is slidably inserted into the viewfinder socket. To this end, the contact strip is mounted in a recess in the base plate and is covered by another yieldable contact strip which is employed as a counter contact and is caused to be pressed downwardly, and which connects its contact pin with the countersunk contact only when the flash gun has been attached to the camera. At least the area of the contact strip in the region of the recess accommodating a contact in the base plate is made substantially smaller than the tip of a finger so that at an unintentional touching by the finger tip the latter will rest on the fixed base Patented Nov. 28, 1967 plate and a depressing of the contact strip to contact making engagement is prevented.

Another possibility to close the switch in the viewfinder socket by the insertion of the flash gun into the socket consists in that a contact strip cooperating with the center contact of the flash gun attachment plug extends into one of the two spaced parallel guide grooves of the viewfinder socket where the base plate has an opening. When the attachment plug of the flash gun is slidably inserted into the viewfinder socket, the contact strip connected to this attachment plug comes into engagement with another contact strip which is connected to the contact nipple on the camera, preferably under interposition of an insulator.

The contact strip cooperating with the center contact of the flash gun attachment plug is preferably countersunk into the base plate of the viewfinder socket.

The drawing illustrates by way of example two embodiments of the invention which will be explained in more detail hereinafter.

In the drawing:

FIG. 1 is a longitudinal sectional view taken along the longitudinal center line of a viewfinder socket attached to the top wall of a camera casing and with the attachment plug of a flash gun inserted therein;

FIG. 2 is a partial cross-sectional view of another viewfinder socket which is provided with a switch adapted to be closed when an attachment plug for a flash gun is inserted into the socket of which only the left hand guide groove is shown, and

FIG. 3 illustrates a wiring diagram of the flash gun arrangement.

FIG. 4 is a top elevational view showing the form of the invention illustrated in FIG. 1; and

FIG. 5 is a side elevational view partly in section of the form of the invention illustrated in FIG. 2.

Referring to FIG. 1, the camera top wall 1 has mounted thereon a viewfinder socket 2 in which the attachment plug 3 of a flash gun is slidably inserted from the right hand side. The viewfinder socket 2 and the attachment plug 3 are grounded, i.e. connected to the metallic body of the camera casing. The viewfinder socket 2. has mounted therein a contact 4 insulated against ground and somewhat below the upper face 5 of the base plate 11 of the viewfinder socket 2. The contact 4 comprising a prong extending outwardly from a contact strip 4a is electrically connected in a manner not shown with the voltage carry ing pole of the contact nipple. In the attachment plug 3 is yieldably mounted an insulated contact 6 which is under the action of a spring 7. The contact 4 in the socket 2 is covered by a leaf spring 8 which is also mounted with one end connected to the insulating plate 10 and electrically insulated in the viewfinder socket 2, namely in such a manner that when the attachment plug 3 is not inserted in the viewfinder socket 2, the leaf spring 8 will not touch the contact 4. Upon slidably inserting the plug 3 into the viewfinder socket 2, the contact 6 at first will assume the position illustrated in dash and dotted lines in which the leaf spring 8 is not yet depressed. Upon moving the plug 3 farther toward the left until its front end 3a reaches an abutment 9, the contact 6 in the plug 3 under the action of the spring 7 depresses the leaf spring 8 so that the latter comes into engagement with the contact 4 and thus establishes the desired electric connection between the attached flash gun and the synchronous contact built into the camera. Since the yieldable contact 6 does not cooperate directly with the contact 4 but only by way of the leaf spring contact 8, a certain amount of free vertical movement is given for the position of the contact 6 within the socket 2 so that small deviations in the dimensions of the plug 3 do not influence the contact engagement. The force of the spring 7 which acts upon the attachment plug contact 6 has to be greater than the tension of the leaf spring 8 in order to ensure an engagement between the contacts 4 and 6 when the flash gun plug is inserted in the viewfinder socket.

The leaf spring 8 is attached with one end to an insulating plate 10 which is provided with a cut-out which receives the free end of the depressible leaf spring 8 for the purpose of engaging the contact 4. The insulating plate 10 is arranged below the base plate 11 of the viewfinder socket 2. The base plate 11 has a corresponding cut-out 11a into which extends in addition to one end of the leaf spring 8 also a certain portion of the insulating plate 10 next to the leaf spring 8. The area of the leaf spring 8 exposed by the cut-out in the base plate 11 preferably is substantially smaller than the tip of a finger so that upon an inadvertent touching of the leaf spring 8 the finger tip comes to lie on the base plate 11 or the insulating plate 10, respectively, thus preventing an accidental depressing of the leaf spring 8.

According to another embodiment of the invention as shown in FIGS. 2 and 5, a contact strip 12 arranged spaced from and parallel to the contact strip 412 extends laterally into the region of one of the guide grooves 13 of the viewfinder socket 2b of which only the left hand portion is illustrated. The contact strip 12 is arranged below the base plate 511 of the socket 212 which at least is partly formed of insulating material. The contact strip 12, is conductively connected at one end with a contact plate 14 arranged in the center of the viewfinder socket 2b and cooperates with the center contact 6 of the attachment plug 3 of the flash gun. The other end of the contact strip 12. which lies adjacent the guide groove 13 carries an insulator body 15 which extends through an opening 16 in the base plate b. The insulator body 15 is protected against falling out of the opening 16 by a leaf spring 17 arranged in the guide groove 13. When the attachment plug 3 of the flash gun is inserted in the viewfinder socket 2b, the leaf spring 17 is depressed. This establishes a contact, via the insulating body 15, between the parallel contact strips 12 and 4b, and at the same time the yieldable contact 6 in the plug 3 engages the contact plate 14 so that the flash gun is connected with the electric circuit which contains the synchronous contact in the photographic camera.

In both examples of the invention the viewfinder socket and the attachment plug of the flash gun serve as ground conductors. When this is not the case, double contacts are required in the viewfinder socket as well as in the attachment plug to which the invention is also applicable.

What we claim is:

In a photographic camera having a planar surface on which is mounted a viewfinder socket provided with spaced parallel guide ribs, the combination of said viewfinder socket with a switch and an attachment plug longitudinally slidable between said guide ribs for the detachable connection with a flash gun, a base plate having a longitudinal opening mounted above said surface so that the opening will register with an opening in said planar surface, said switch including a first contact member mounted on said base plate extending normal-1y in the plane of said planar surface and below the upper surface of said base plate, means insulating said contact member from said viewfinder socket, and a second contact formed of a flexible strip also extending parallel with said first contact member, said flexible strip being connected to an insulating plate arranged below said base plate and projecting over the recess therein, said flexible strip. being moved into conductive engagement with said first contact member when said attachment plug is slidably inserted into said viewfinder socket between said guide ribs,

the area of said contact strip which projects'over said recess being substantially smaller than the tip of a finger so that accidental engagement of the finger with said contact strip will cause said fingertip. to touch a minor portion of said strip so that said contact strip will be insufiiciently flexed to move the same into electrical engagement with said first contact member.

References Cited UNITED STATES PATENTS 2,826,652 3/1958 Piplack 20051.09

2,800,807 7/1957 Gomersall et al. 200.1-38

3,249,725 5/1966 Hutt et al 200-453 FOREIGN PATENTS 1,111,273 7/1961 Germany.

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner. 

